This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. xc2xa7119 from my application APPARATUS AND METHOD FOR AUTOMATICALLY CONTROLLING SCREEN STATUS OF LIQUID CRYSTAL DISPLAY filed with the Korean Industrial Property Office on Jul. 20, 1999 and there duly assigned Serial No. 29386/1999.
1. Technical Field
The present invention relates to an apparatus and a method for automatically controlling the screen status of a liquid crystal display. More specifically, the present invention relates to an apparatus and a method for automatically controlling the screen status of a liquid crystal display in which, when the externally inputted analogue video signals are converted to digital signals, the frequency and phase of the sampling clock signals are shifted, thereby maintaining the optimum screen status.
2. Related Art
Generally, a flat panel display (to be called xe2x80x9cFPDxe2x80x9d), such as liquid crystal display, can be made thin and light unlike the cathode ray tube (CRT) monitors. Further, the images can be displayed in a clear form without distortion. Therefore, the application of the FPD is being expanded widely, even to notebook computers.
In the FPD, analogue signals have to be converted to digital signals, so that the analogue interface environment for the CRT monitor can be supported. Accordingly, in order to convert the analogue signals to digital signals, clock signals are generated.
In this situation, if the signal source is not exactly matched with the phase of the clock signal, then the picture quality is deteriorated. Therefore, each time that a change occurs in the signals source, the phase of the sampling clock signals has to be adjusted.
In such a system, one solution is to require the user to manipulate a screen control key while observing the display panel in the expectation of shifting the phase of the sampling clock signals, thereby adjusting picture quality.
However, this can cause inconvenience to the user. Moreover, many users do not have the experience or the knowledge to be able to manipulate screen control properly so that adjustment of picture quality is not achieved.
Therefore, there is a need for the development of an apparatus and method for automatically adjusting or controlling the screen status of a liquid crystal display so as to properly shift the phase of the sampling clock signals and achieve proper adjustment of picture quality.
The present invention is intended to overcome the above described disadvantages of the conventional technique.
Therefore, it is an object of the present invention to provide an apparatus and a method for automatically controlling the screen status of a liquid crystal display in which, when the externally inputted analogue video signals are converted to digital signals, the frequency and phase of the sampling clock signals are shifted, thereby maintaining the optimum screen status.
In a first aspect of the present invention, in achieving the above object, the apparatus for automatically controlling the screen status of a liquid crystal display according to the present invention includes: a PLL circuit section for converting the frequency of sampling clock signals in response to externally inputted control signals; an A/D converter for converting analogue video signals of a computer main body to digital signals in response to the sampling clock signals of the PLL circuit section; a graphic control section for scaling the digital signals of the A/D converter in response to externally inputted control signals so as to display picture signals on a display panel; a data generating section for receiving the video signals from the A/D converter and calculating differences between adjacent video signals so as to sum up the differences thus calculated, and to form first comparison data; and a microcomputer for converting the frequency of the sampling clock signals by using reference data, so as to output control signals and to convert the frequency of the clock signals of the PLL circuit section, for comparing the first comparison data of the data generating section with reference data so as to detect a maximum value, for controlling the sampling clock signals to have a present frequency, and for recognizing a resolution of a video mode of the computer main body so as to control the overall system.
In a second aspect of the present invention, the apparatus for automatically controlling the screen status of a liquid crystal display according to the present invention includes: a PLL circuit section for converting the frequency of sampling clock signals in response to externally inputted control signals; an A/D converter for converting analogue video signals of a computer main body to digital signals in response to the sampling clock signals of the PLL circuit section; a graphic control section for scaling the digital signals of the A/D converter in response to externally inputted control signals so as to display picture signals on a display panel; a data generating section for detecting first and last points of horizontal lines of the video signals of the A/D converter to sum up the points thus detected so as to form second comparison data; and a microcomputer for converting the frequency of the sampling clock signals by using reference data, for outputting control signals to convert the frequency of the clock signals of the PLL circuit section, for comparing the second comparison data of the data generating section with reference data to detect a maximum value, for controlling the sampling clock signals to have a present frequency, and for recognizing the resolution of a video mode of the computer main body so as to control the overall system.
In a third aspect of the present invention, the apparatus for automatically controlling the screen status of a liquid crystal display according to the present invention includes: a PLL circuit section for converting the frequency of sampling clock signals in response to externally inputted control signals; an A/D converter for converting analogue video signals of a computer main body to digital signals in response to the sampling clock signals of the PLL circuit section; a graphic control section for scaling the digital signals of the A/D converter in response to externally inputted control signals so as to display picture signals on a display panel; a data generating section for receiving the video signals from the A/D converter so as to calculate differences between adjacent video signals and to sum up the differences thus calculated so as to form first comparison data, and for detecting first and last points of horizontal lines of the video signals of the A/D converter to sum up the points thus detected so as to form second comparison data; and a microcomputer for converting the frequency of the sampling clock signals by using reference data, for comparing the first and second comparison data of the data generating section with respective reference data to detect respective maximum values, for controlling the sampling clock signals to have a present frequency, and for recognizing the resolution of a video mode of the computer main body so as to control the overall system.
In a fourth aspect of the present invention, the method for automatically controlling the screen status of a liquid crystal display according to the present invention includes the steps of: (1) initializing a memory, the memory having a predetermined number of times of outputting; (2) receiving comparison data from an outside source; (3) determining whether the comparison data is larger than predetermined reference data; (4) replacing the reference data with the comparison data and storing it if the comparison data is larger than the reference data, and storing the reference data as it is if the comparison data is smaller than the reference data; (5) counting the number of receptions of the comparison data; (6) determining whether the number of the counted times is same as a set number of times; and (7) controlling the sampling clock signals by using the reference data if the counted number of times is the same as the set number of times, and returning to step (2) and repeating from step (2) on if the counted number of times is less than the set number of times.